From: Ryan Roberts ryan.roberts@arm.com
mainline inclusion from mainline-v6.9-rc1 commit 2bdba9868a4ffcb1492db7272f34b54387910177 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CUEQ CVE: NA
-------------------------------------------------
Refactor __split_huge_pmd_locked() so that a present PMD can be collapsed to PTEs in a single batch using set_ptes().
This should improve performance a little bit, but the real motivation is to remove the need for the arm64 backend to have to fold the contpte entries. Instead, since the ptes are set as a batch, the contpte blocks can be initially set up pre-folded (once the arm64 contpte support is added in the next few patches). This leads to noticeable performance improvement during split.
Link: https://lkml.kernel.org/r/20240215103205.2607016-3-ryan.roberts@arm.com Signed-off-by: Ryan Roberts ryan.roberts@arm.com Acked-by: David Hildenbrand david@redhat.com Cc: Alistair Popple apopple@nvidia.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Ard Biesheuvel ardb@kernel.org Cc: Barry Song 21cnbao@gmail.com Cc: Borislav Petkov (AMD) bp@alien8.de Cc: Catalin Marinas catalin.marinas@arm.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Ingo Molnar mingo@redhat.com Cc: James Morse james.morse@arm.com Cc: John Hubbard jhubbard@nvidia.com Cc: Kefeng Wang wangkefeng.wang@huawei.com Cc: Marc Zyngier maz@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Will Deacon will@kernel.org Cc: Yang Shi shy828301@gmail.com Cc: Zi Yan ziy@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit 2bdba9868a4ffcb1492db7272f34b54387910177) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com --- mm/huge_memory.c | 58 +++++++++++++++++++++++++++--------------------- 1 file changed, 33 insertions(+), 25 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 2073693b3aa7..cd1eb575f15d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2408,15 +2408,16 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
pte = pte_offset_map(&_pmd, haddr); VM_BUG_ON(!pte); - for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { - pte_t entry; - /* - * Note that NUMA hinting access restrictions are not - * transferred to avoid any possibility of altering - * permissions across VMAs. - */ - if (freeze || pmd_migration) { + + /* + * Note that NUMA hinting access restrictions are not transferred to + * avoid any possibility of altering permissions across VMAs. + */ + if (freeze || pmd_migration) { + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { + pte_t entry; swp_entry_t swp_entry; + if (write) swp_entry = make_writable_migration_entry( page_to_pfn(page + i)); @@ -2435,25 +2436,32 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, entry = pte_swp_mksoft_dirty(entry); if (uffd_wp) entry = pte_swp_mkuffd_wp(entry); - } else { - entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); - if (write) - entry = pte_mkwrite(entry, vma); - if (!young) - entry = pte_mkold(entry); - /* NOTE: this may set soft-dirty too on some archs */ - if (dirty) - entry = pte_mkdirty(entry); - if (soft_dirty) - entry = pte_mksoft_dirty(entry); - if (uffd_wp) - entry = pte_mkuffd_wp(entry); + + VM_WARN_ON(!pte_none(ptep_get(pte + i))); + set_pte_at(mm, addr, pte + i, entry); } - VM_BUG_ON(!pte_none(ptep_get(pte))); - set_pte_at(mm, addr, pte, entry); - pte++; + } else { + pte_t entry; + + entry = mk_pte(page, READ_ONCE(vma->vm_page_prot)); + if (write) + entry = pte_mkwrite(entry, vma); + if (!young) + entry = pte_mkold(entry); + /* NOTE: this may set soft-dirty too on some archs */ + if (dirty) + entry = pte_mkdirty(entry); + if (soft_dirty) + entry = pte_mksoft_dirty(entry); + if (uffd_wp) + entry = pte_mkuffd_wp(entry); + + for (i = 0; i < HPAGE_PMD_NR; i++) + VM_WARN_ON(!pte_none(ptep_get(pte + i))); + + set_ptes(mm, haddr, pte, entry, HPAGE_PMD_NR); } - pte_unmap(pte - 1); + pte_unmap(pte);
if (!pmd_migration) folio_remove_rmap_pmd(folio, page, vma);